Island



(NovModel.)

W. H. SAWYER.

.BLBGTRIG CIRCUIT OPENER. No. 311,681. Paented Feb. 3, 188.5.

l UNITED STATES PATENT OFFICE.

VILLIABI H. SAVYER, OF PROVIDENCE, RHODE ISLAND. d

ELECTRIC-CIRCUIT OPENER.

SPECIFICATIOQT forming part of Letters Patent No. 311,681, dated February 3, 1885.

Application tiled January 2:2, 1854.

.To aZZ whom it may con/cern,.- V

Be it known that I, WILLIAM H. SAWYEE,

d 'a citizen of the United States, residing at Providence, in the count-y of VProvidence and State of Rhode Island, have invented certain new and useful Improvements in Electric- Circuit Openers, of which the following is a specication, reference being had therein to the accompanying drawings.

My invention relates to improvements in automatic electric-circuit openers of that class in which a. conductor of comparatively high resistance becomes heated when the circuit remains closed for an unduly long period, and causes fusion or softening ot'a substance which maintains the continuit)7 of the circuit when solid and in its normal position, but when -fused or softened allows the circuitconduct ors to become separated. Electric circuits;

employed for lighting gas,annunciators, bnrglar-alarms, and many other uses are usually normally open, and are closed only for brief periods at intervals for operating the includi ed instruments. The bat-teries used on such circuits are almost always of the kind known as open-circuit batteries, which waste rapidly on closed circuit, and soon run down, so as to be unfit for use. The class of circuits referred to are liable to be closed too long from various causes-as, for instance, the failure of puslrbutton and keyl contacts to be come separated when the pressure is removed,

`forgetfulness of attendants to open circuitclosing switches, and accidental grounding of wires.

The object of my invention is to provide a cheap and reliable device which may be conveniently interposed in any electric circuit. and will promptly open the saine it' it remains closed for a longer period than necessary or usual for accomplishing the intended purpose.

lily invention will be fully understood from the following particular description, in connection with the accompanying drawings, in which- Figure l is a viewvin elevation of a circuitopener constructed according to my invention. Fig. 2 is a longitudinal central sec tion of thelsame.' Fig. 3 is a perspective view of a series of the circuit-openers mounted in .a box and arranged to be included in different circuits. Fig. 4 is-a transverse section 0f the box in aplane cutting longitudinally (No model.)

\ the metallic spring-arms supporting one of the circuit-openers. Figs. 5 and 6 are diagrams illustrating` preferred arrangements of the circuit-openers and accessories on long' circuits.

In the drawings, the letter A indicates a glass tube, which, in practice, is preferably about one fourth of an inch in diameter and an inch and a halt' long, though the dimensions of the tub'e are unimportant. In the ends of this tube are inserted wooden or other Stoppers or plugs, B and B', and through the stopper B is arranged a headed metal piu or screw, C, having a transverse hole through its projecting inner end, while through the other stopper or plug, B. is arranged a headed metal pin or screw, C', which is hollow or bored longitudinally.

To the inner end of the screw or pin C is attached one end of a short piece of fine platinum or German-silver wire, E, the opposite end of which is lapped and preferably slightly twisted, as shown atf, Fig. 2, with the end of another fine platinum or'Germau-silver wire E, which has its other end looped to aheavier wire, E2, which is coiled or bent. as shown at e, to form a spring. The joint, f, betweenthe two wires is secured by embedding it in a mass, g, of readily-fusible non-metallic adhesive substance which melts at a low temperature-for example, a cementing wax such as is used by jewelers in securing small articles to lathe-mandrels. A non-metallicsubstancesuch as wax--is preferable forembedding the flap-joint, for the reasonthat it permits a more the tube, the wires being first inserted into the same with the end'of wire E2 projectinfr- The end of this wire EZ is then passed through the hollow pin orscrew C', the stopper B is inserted in the end of the tube opposite stop per B, as shown, and the wire E2 isdrawn'ontward taut enough to place the'spring portion f under a considerable tension, but notenough e lrsi to break the jointf as secured by the readilyfusible substance g. -The projecting portion of the taut `wire E2 is then secured to the pin or screw C by soldering or by winding it around and snugly under the head of said pin or screw. AThe circuit-opener is thus completed, and it is to be understood that thelap of the two wires E and E is of such extent and the tension of the spring e such that if the securing mass of readilyfusible substance g were removed or softened the tuo wires would be separated by contraction of the `spring. If theA circuit-opener should be included in an electric circuit by connecting the screws or pins C and C to opposite terminals or electrodes, and a current of sufficient strength placed on the circuit to heat the wires E and E', or either of them, the readily-fusible mass g would be melted or softened so as to lose its hold upon the wires, which would be then separated and the circuit broken by the action of the spring e, as before explained.

In Figs. 3 and 4 I have illustrated simple and very convenient means which I have invented for including the circuit-opener in a circuit.

The letter II designates a wooden box, having a door, l1, provided with a glass or other transparent pane, h', through which the interior of the box may be observed when it is closed. lI`he back of the box in the present instance is formed of three pieces, t', i', and t, and to the back of the center piece, i2, are se` cured elastic metallic strips tand k', which are bent across its opposite edges so as to pro ject into the box and form the supportingarms, between which is held the circuit-opener, as shown, said arms having cavit-ies or recesses, as at Z Z, formed in their facing-surfaces to receive heads of the screws or pins C and C'. The arms also havetheir free ti ps inclined from each other, so that the circuit-opener may be placed in position by simply pressing it in between these tips and the arms until its pin or screw heads reach the cavities prepared for them. The arms k and la are respectively connected by wires m and m with binding-posts P andN, by which they may be connected in a circuit, in the usual manner. The box may contain as many circuit-openers as desired, and when there are several circuits in the same building or leading from the same battery or locality, I prefer, for Convenience, to inclose the circuit-openers for all in the same box. It' at any time, on closing a circuit, it is found that the instruments in the same do not oper- Vate, it will usually be found on inspection that the fine wires of the circuit-opener in such circuit are separated, the separation 'having taken place alter a previous closing. which (ont-inued for a length of time sntiicicnt to heat said wires and melt or selten the wax or alloy, as before explained. ln order to place the circuit again in operative condition. the now unserviccable circuit-opener may be withdrawn from its supporting-arms and replaced by a new one. Before doing so, however, 'the attendant should temporarily connect the arms kand k' by a short rod or awire to test whether or not the circuit is otherwise intact. It will be understood that the size of the fine wires E and Eis so proportioned to the strength of the current lused on the circuit that a brief closing of the circuit will not cause such heating of said wires as will melt the wax or alloy; but if the current remains on the circuit longer than the usual time required for operating its instruments, said wires will become heated with the result already stated.

When the'circnit-opener as now described is used in connection with a very long circuit, it may be found desirable to provide for placing a portion of the main battery or an extra battery on a short circuit through the tine wires E and E', in order to insure theheating of said wires.

In Fig. 5 I have illustrated an arrangement of devicrs by means of which a portion ofthe main battery of a gas-lighting circuit is placed on a short circuit through the circuit-opener when the main line is closed. L is a portion of the main circuit leading from one pole of the battery X through the circuit-opener. as shown, to a metal contact-point, q, from which another portion, L', leadsthrough the coils of electro-magnet B and onto ground through the instruments to be operated. An armature, S` is arranged to be attracted by the magnet R to make contact with the point q. From an intermediate portion ofthe batterya wire, L, leads to the armature S from va plate of opposite character to that from which the main circuit-conductors lead. It will now be obvious that when the main circuit is closed the current will first flow as indicated by the arrows No. 1, the magnet R will attract its armature into contact with point q, and thus close a short circuit, over which a portion of the battery-current will flow back to part of' the'battery, as indicated by arrows No. 2.

In Fig. 6 the main circuit, circuit opener, magnet, armature, and contact-point are arranged and lettered as shown in Fig. 5; but, instead of placing a part of the main battery on a short circuit` I connect one pole of the main battery and a similar pole of an extra battery, X', with one end of the circuit-opener.. and the opposite pole of this extra battery I connect to the armature S of the magnet by a wire, L. In this case, when the main circuit is Vclosed and the magnet attracts its armature to point q, the main current will flow through the circuit-opener, as shown by arrows No. 1, and the current of batteryX will also tlow through the circuit-opener on short circuit,as shown by arrows No. 2. In this arrangement the main and auxiliary batteries must be of equal electro-motive force and the external resistances properly arranged to prevent either battery t'rom dis-advantageously counteracting the other. The main difference between the plans of Figs. 5 and 6 is that in Fig. 5 the re- IOO IIC

tractile spring t of the armature must be ad euit is broken by the circuit-opener the part ofthe battery on short circuit will not be strong enough to cause the magnet to hold down its armature, as that would keep the main portion of the battery on the line through wire L2 and the armature.

In Fig. 6 the circuit-opener will break both battery-circuits simultaneously, and a high adj ustment of the armature-springisof course not necessary.

It is not essential to use wooden or other non-conducting,r Stoppers for the tube A, it being itself a non-conductor, and the metal pins to which the fine wires are attached might be large enough to it snugly in the ends of the tube. I prefer, however,to use wood or cork, on account of their eheapuess and the elasticity which holds stoppers of such materials in place. The tube might be replaced by simple non-conducting bars or an open frame to keep the fine wires properly taut, so far as actual use is concerned; but the tube protcctsthe inclosed parts in handling and packing, and is as cheap and etticient support for the other parts as could well be contrived, and I therefore prefer to use it.

I wish it to be understood that I do not confine myself to the particular details of construction which I have shown for earryingont any part of my invention, but may vary the same in any manner which circumstances may suggest without departing from' its essential principles. 4

I am aware that a strip of readily-fusible metal has been included iu a circuit for breaking the same by its fusion when the circuit remains closed too long or too strong a current ilows thereon; and I am also aware that a stick of wax has been arranged Ato support two spring-terminals of a circuit in contact with ea'eh other and to be melted by the heating` of a surrounding coil of tine wire, and so removed to allowthesprings to separate when the circuit remains closed longer than necessary. I do notclaim either of such circuitopeners.

Instead of attaching the tine wire E to a 'separate wire, which is coiled to, form a spring, I may make the tine wire long enough to pass through the plug, and have a portion .of its length coiled to form t-he spring; or I may attachl the said lfine wire to a strip of elastic rubber attached to the plug, and conneet the end of said wire also to the metal pin or screw by a slack wire, which will permit thel rubber strip to contract when released from tension by the parting ofthe two tine wires. f

Iam aware that in an electrical cut-out or circuit-opent r two wires under tension have had their ends lappedand held together by'a readily-fusible metallic solder, and I do notl claim such a construction, broadly,

I am aware that in a circuit-opener a mass of readily-fusible.r nonconducting material has been arranged to hold apart two metallie plates pressed toward each other by a spring, said plates being electrically connected by fine pliable wires extending from one plate to the other through the interposed non-conducting and readily-fusible mass, the operation being that when the circuit-opener is interposed between two electrodes with its plates in contact with said electrodes, respectively, a current of` excessive strength will heat the fine wires connecting the plates',

-the mass embedding said wires will be melted and allow the spring to force the plates toward eachother, bending the intermediate fine wires and breaking connection with,one or the other of the said electrodesgthus opening the circuit. The elect-rodes between which the circuit-opener is placed have been simply two rigid and rigidly-supported metal plates, one of which must be removed in order to replace an old circuit-opener by a new one. or the means referred to for supporting it.

IVliat I claim s- 1. In an electric-circuit opener to be oper-V ated by heat generated by an electric current traversing the circuit, the combination, with the lapping tine wires anda spring tending to draw them apart, ot' the mass of non-metallic adhesive substance readily fusible by I lay no claim to such acireuit-opener 5 heat and embcddingt-he lap-joint ofthe wires, 9

substantially as described.

2. In a circuit-opener, the combination, with the lapping tine wires of high resistancc, one having a spring connected therewith, and the mass of substance easily softened or melted by heat inclosing and seeuring the lap-joint of said wires, of the transparent non-conducting tube' inclosing said wires, and metallic connecting attachments for said wires arranged in the opposite ends of said tube, substantially as described.

3. The combination of the tine-wire E, the lapping tine wire E and attached wire E, having a portion thereof bent or coiled to form a spring, c,\the glass tube inclosing said wires, and the metallic supports for said wires arranged in the ends of said tube, substantially as described.

et. The eonibination,with the circuit-opener composed ofthe line` wires under tension and held in lapping contact by a mass of substance embedding their lap-joints and readily fusible or softened by heat, 'ot' the metallie spring-arms arranged to receive and'support said circuit-opener between them and -come in electrical connection with said tine presence ot' two witnesses.

Witnesses: WILLIAM Il.' SAWYER.

GILMAN E. .Tore FRANK S. MEAD.

TOO

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